The invention relates to a high gradient magnetic separator comprising a matrix of parallel wires which can be magnetized and are arranged in planes each of which includes a channel with a non-magnetic wall, which extends between two parallel wires and through which fluid including magnetic particles can be conducted, and an arrangement for generating in the matrix a magnetic field which extends normal to the planes which are defined by the wires and channels.
A general overview concerning the various types of magnetic operators as well as their applications is presented in the reference [1]. In accordance therewith coarse, highly magnetic particles such as magnetite ores with a particle size  greater than 75 xcexcm and highly magnetic finer particles can be separated from aqueous suspensions up to a size of about 10-20 xcexcm with simple drum or belt separators. For still finer particles in the micrometer range, so far only the so-called high gradient magnet separation is used whose principle of separation is based on the generation of strong field strength gradients by introduction of a ferromagnetic matrix structure into an outer magnetic field. The matrix structure generally consists of irregularly arranged steel wool or, respectively, systematic wire nets or profiled metal plates. The elements of the matrix structure are magnetized by the outer field and form magnetic poles, which locally strengthen or weaken the outer field. This provides for high field strength gradients resulting in a strong magnetic force on para- or, respectively, ferromagnetic particles in the direction of the greater field strength. The particles attach themselves to the induced magnetic poles of the matrix and consequently are separated from the fluid.
[2] discloses another high gradient magnetic separator for the continuous separation of particles from a fluid flow including magnetic particles (in the example given: ore suspensions) into partial fluid flows each enriched with non-magnetic and, respectively, magnetic particles. With this high-gradient magnetic separator, the previously prepared particle-containing fluid is conducted into a non-magnetic tube. The tube extends into the separation zone in which magnetic wires are arranged in parallel at uniform distances from one another to form a matrix structure. With the application of an outer magnetic field, which can be generated by a permanent magnet, an electromagnet, a super-conductive magnet or a cryo-technical magnet, the wires are magnetized whereby a field of magnetic force gradients is formed around the wires. Consequently, the magnetic particles in the fluid flow are concentrated in this field in the areas of the highest magnetic field strength, that is, directly at the magnetic poles or wires. As a result, during continuous operation, the separator will be clogged by particles collected on the magnetic poles of the wires. Directly following the separation zone, the fluid is directed, shortly before leaving the outer magnetic field, into a channel structure whose inlets are so arranged that the fluid flow is divided and exits the arrangement in a flow enriched with magnetic particles and a depleted flow.
An apparatus for a continuous magnetic separation capability with substantially lower clogging tendency during continuous operation is disclosed in [3]. Important herein is that the separation zone, which has an elongated cross-section and into which the magnetic particle-containing fluid is conducted has a non-magnetic wall. To the separator, a magnetic field is applied whose field lines extend in the separation zone ideally normal to the flow direction of the fluid and normal to the longest axis of symmetry of the flow cross-section. In order to generate the magnetic field gradients necessary for the magnetic separation of ferro-, para-, and diamagnetic particles, a single magnetizable wire is arranged at a front end of the elongated cross-section of the separation zone parallel to the flow direction of the fluid. Still under the influence of the magnetic field, the separation zone is divided into several channels which separate the fluid into different fractions, which differ by the content of magnetic particles. The apparatus is also described in [4] wherein an additional embodiment is disclosed which includes two magnetizable wires (instead of a single wire) each extending at the front ends of the elongated cross-section of the separation zone parallel to the flow direction. The apparatus however, by its design as described, has to have a certain size which limits its applicability particularly for larger fluid flows.
A high gradient magnetic separator of the type referred to initially with a very compact matrix-shaped cross-section arrangement of the separation zone which is suitable also for larger fluid flows as they actually occur, is described in [5]. It is provided with magnetizable wires which are arranged alternately with rectangular channels which are disposed parallel to the wires in a line-like fashion, wherein the individual lines are separated from one another by paramagnetic intermediate plates. For the separating procedure, a magnetic field is applied in a direction normal to the lines and the intermediate plates. However, no actual examination of the concept is described in [5] nor is any technical solution disclosed for the supply and the removal of the fluid to be separated.
It is the object of the present invention to provide a high gradient magnetic separator with channels in the area of the separation zone in such a way that the efficiency of the apparatus is increased over those known in the state of the art. Furthermore, a discharge flow arrangement is to be provided which is accurately adapted to the partial flows of the fluid being separated.
In a high gradient magnetic separator with a separation zone consisting of a matrix of parallel magnetic wires arranged in parallel planes and channels formed by a non-magnetic material and extending in each plane between adjacent parallel magnetic wires for conducting a fluid including magnetic particles through the matrix, and a magnetizing structure disposed adjacent the matrix for generating a magnetic field with field lines which extend essentially normal to the parallel planes, separating walls are disposed in parts of the channels in the area ahead of the end of the magnetic field generated in the matrix and adjacent the flow exit end of the matrix so as to extend parallel to the planes and normal to the magnetic field lines and form partial flow channels receiving partial fluid flows of magnetic particle-enriched and, respectively, magnetic particle-depleted flow volumes.
In the area of magnetic field gradients freely movable magnetic particles, which are suspended in a solution, will basically collect in the area of the highest magnetic strength. In this respect, not only the magnetic forces components which are oriented radially to the magnetizable wires, are acting on these particles but also the magnetic forces components extending tangentially to the wires. These tangential magnetic force components have been taken into consideration in the design considerations for the channel cross-sections in the separation zone of the high gradient magnetic separator according to the invention. The arrangement according to the invention results in the generation of magnetic force gradients with radial and tangential orientations in the flow cross-section in such a manner that the magnetic particles contained in the fluid flow can be concentrated during the passage through the separation zone as completely as possible in a small partial fluid flow. Consequently, the high gradient magnetic separator according to the invention hasxe2x80x94in contrast to the prior art arrangement last mentionedxe2x80x94an elliptical or circular cross-section for the channels in the separation zone.
The magnetic particles are enriched in flow direction in the separation zone in segments of the elliptical or circular channels, which are turned by 90xc2x0 with respect to the row structure. Still within the separation zone, that is, within the magnetic field, separating walls are disposed within the channels which extend parallel to the row structure and which divide the flow into partial flows with, and without, magnetic particles.